A vehicle de-rate occurs when a reduction of available vehicle function is imposed on a vehicle without being requested by an operator. For example, an engine de-rate can be imposed (e.g., by electronic controls) on a vehicle in order to reduce engine speed or engine torque. A de-rate can be imposed on a vehicle in order to achieve a desired effect that stems from the de-rate, such as reduction of vehicle emissions.
U.S. Pat. No. 7,480,559 describes a method to operate an internal combustion engine having electronic control to detect emissions, compare the emissions to stored emissions at given engine speeds and torques, and de-rate the engine if the actual emissions are outside the range of calculated emissions for a given engine speed or torque; and a method to operate an electronic-controlled internal combustion engine to detect failures or impending failures in an emission system and de-rate engine speed or engine torque by an amount sufficient to reduce emissions levels to calibrated emissions levels and render an indication to an operator of the failure or impending failure.
However, prior systems have failed to provide a comprehensive treatment of possible de-rate causes and related information that can be communicated to operators.